The present invention generally relates to methods and apparatus for peeling or delaminating a composite sheet structure such as, for example, a laminate containing image media. The laminate may be used to provide a "master" image. Prior to peeling, the image is typically produced in the laminate by thermal imaging enabling a high resolution image to be achieved. For a more detailed description of the laminate composition to which the present invention may be applied, reference may be had to commonly assigned International Patent Application No. PCT/US 87/03249 published Jun. 16, 1988 under International Publication Number WO 88/04237; and U.S. Pat. No. 5,200,297. After this laminate has been imaged, it is delaminated by peeling one layer therefrom and having the remaining imaged media relaminated with a protective coating. For a more detailed description of the imaging technique and associated peeling process, reference is made to commonly assigned U.S. Pat. Nos. 5,141,584 to Schuh et al. and 5,159,352 to Ferla et al. The present invention may also be applied to other laminates, for example those used to make printed circuit boards.
In the peeling process, a take-away layer is peeled from an image-forming layer adhered to a substrate of the laminate by passing the laminate through the nip of peel rolls while the take-away layer is peeled and moved about the upper peel roll. However it is now known in the art that the step of dry peeling can produce defects in the image. This is due in part to the alternating high and low density areas in the image forming layer produced by thermal imaging.
Imaging defects can also be produced by debris or extraneous particles from various sources accumulating on the laminate during travel from the point of manufacture to the peeling station, whereby such debris tends to accumulate on the rotating peel rod and causes formation of image artifacts in the image-forming layer. It has therefore been found to be very important to eliminate debris from the peel roll or rod in order to prevent the formation of the noted artifacts.